"In order to advance serious negotiations, we will all need to take decisions and prove we are determined to reach an agreement and real peace. That burden of proof is also on the Palestinians' shoulders," she was quoted on her Facebook page as saying.

"Accordingly, we will examine the issue of the prisoners, meaning that the key to the cells of the Palestinian prisoners is also to be found in the hands of Abu Mazen (Abbas) and the decisions he will take in the coming days."

Livni's remarks came after Israeli officials suggested the release might not go ahead unless the Palestinians agree to extend talks beyond a looming April 29 deadline.

Livni denied she was trying to finger point, but said she was raising the issue "before decisions are taken" as the two sides mull whether to move into a second phase of US-led negotiations.

So far, 78 of 104 veteran Palestinian prisoners have been freed in three tranches, with the final group due to be released on March 29, pending approval by the Israeli cabinet.

But senior officials, quoted by the Makor Rishon daily's diplomatic correspondent on Twitter, said that "without an explicit commitment by Abu Mazen to extend the talks, there will not be a fourth wave" of releases.

Peace talks relaunched last July have made next to no progress, marred by bitter disputes over core issues, and Washington is fighting an uphill battle to get agreement on a framework proposal that would extend the process to the year's end.

Earlier, a senior cabinet minister also cast doubt on the planned prisoner release, and said if it did go ahead, it would not include any Arab Israelis jailed for nationalist attacks.

"The (original) decision said (the release) should be dependent on progress in the negotiations and now it is clear to everyone that there has been no progress," Economy Minister Naftali Bennett told army radio.

Bennett, an outspoken hardliner who opposes a Palestinian state, also said Israel had never promised to free Palestinian citizens of Israel.

The Palestinians have reportedly named 14 Palestinian-Israelis they want freed, but all names must be approved by Israel.

"The government of Israel never took any decision to release Israeli prisoners," Bennett said, describing such an idea as "delusional."

Bennett also accused Abbas of staying in the talks purely to ensure another 26 prisoners were freed.

His remarks were made a day after Abbas told US President Barack Obama that releasing the prisoners would be a good step to demonstrate Israel's seriousness about the peace process.

Suggestions that Israel may not follow through with the release have further exacerbated tensions, with Washington working hard behind the scenes to head off a crisis that could deal a death blow to the fragile dialogue between the sides.